In some fuel supply systems for internal combustion engines of, for example, automobiles, fuel is delivered from a fuel tank by a fuel pump at an unregulated pressure to a pressure regulating device, such as a fuel pressure regulator. The fuel pressure regulator delivers fuel at a predetermined pressure to a fuel metering device that, in turn, supplies metered fuel to a fuel delivery means, such as a carburetor or a fuel injection system. The fuel delivery means, in turn, delivers an appropriate air-fuel mixture to the associated engine.
Whether a carburetor or a fuel injection system is employed to deliver fuel to the engine, the fuel delivery means is highly sensitive to any pressure fluctuations in the fuel supply system. An improper fuel pressure or a fluctuating fuel pressure can adversely affect the engine's ability to burn fuel cleanly and operate efficiently to achieve maximum performance. Therefore, it is highly desirable to maintain a steady fuel pressure at the fuel delivery means, particularly for high performance engines.
It is known in the art to regulate the fuel pressure in the fuel supply system with fuel pressure regulators of the diaphragm-and-spring type. Such regulators typically have a fuel inlet chamber for receiving high pressure fuel from the fuel pump, a diaphragm chamber that has a fuel outlet for delivering fuel at a regulated pressure to the fuel metering means, a resilient, impervious diaphragm assembly closing off the diaphragm chamber that is sensitive to pressure fluctuations in the diaphragm chamber, a valve mechanism for controlling fuel communication between the fuel inlet chamber and the diaphragm chamber, and an adjustable spring that biases the diaphragm assembly into the diaphragm chamber and the valve mechanism toward an open position.
The valve mechanism typically comprises a valve seat disposed about a passageway between the fuel inlet chamber and the diaphragm chamber and a valve closure element for closing off the passageway. The valve closure element is connected to and actuated by a valve stem, which extends therefrom and engages at its other end with the diaphragm assembly. So arranged, movement of the diaphragm is imparted to the valve closure element through the valve stem, thereby throttling the flow of fuel through the passageway in response to pressure fluctuations in the diaphragm chamber.
With such diaphragm-and-spring type regulators, it is desirable for the fuel to flow uniformly through the valve passageway so that the flow of fuel does not impart any lateral forces on the valve closure element, causing the valve closure element to misalign itself with respect to the valve seat. Maintaining of the valve closure element in alignment with the valve seat also reduces and more uniformly distributes the wear along the cooperating elements of the valve mechanism, thus improving the overall performance of the regulator.
In order to maintain the valve closure element in alignment with the valve seat, valve guide means typically are provided either at some point along the valve stem or at the valve closure element itself. The valve guide means restrains valve misalignment caused by fuel pressure and vibrations acting against the valve closure element, and by any flexing or sideways movements of the resilient diaphragm imparted to the valve closure element through the valve stem. However, provision of the guide means along the valve stem requires a complicated manufacturing process, while provision of the guide means at the valve closure element itself typically has involved a complicated fuel inlet chamber design to insure that the guide means does not interfere with the flow of fuel through the valve seat. Such complicated designs undesirably add to the cost of the regulator.
In typical fuel pressure regulators, a second biasing means is employed to counterbalance the biasing force of the adjustable spring. This second biasing means typically is a spring positioned adjacent the valve within the fuel flow path. The spring biases the valve closure element against the valve seat. However, positioning of this second spring within the fuel inlet chamber and within the flow of fuel past the valve closure element can have undesirable effects on the performance of the regulator. Preferably, the spring should be located out of the fuel flow path so that it does not restrict the flow of fuel.
Accordingly, a heretofore unaddressed need exists for a fuel pressure regulator having a valve guide means that is simple in design and inexpensive to manufacture, yet which operates accurately to control fuel pressure, and which also has a counterbalancing spring biasing means that does not restrict the flow of fuel through the regulator. It is to the provision of such a fuel pressure regulator that the present invention is primarily directed.